- Auckland: A city on volcanoes
- A. Williams ; A Linzey ; L. Chick
- Book Title / Journal: IAEG2006
- Year: 2006
- Engineering Geology
- Keywords: geological hazards ; geology of cities ; Infrastructure ; volcanic risk
- The Metropolitan area of Auckland, New Zealand, is built on a potentially active volcanic field. The
geologic record indicates that the Auckland Volcanic Field (AVF) is a monogenetic volcanic field in which activity has formed fifty eruptive vents within the last 140,000 years, covering an area of 360 km2. An eruption from this field has the potential to affect the majority of the region's 1.3 million population. Geological
evidence indicates there is a 5 % probability of another eruption occurring from the AVF within the next 50 years, and that the next eruption is likely to be from a new and presently unknown location. While an AVF eruption is expected to cause destruction of a relatively small part of the region (less than 80 km2), indirect impacts on industry, lifeline services, economy and social well-being are likely to have a much wider geographic extent.
Planning response to such an event is complicated because:
• The site of future eruption cannot be predicted;
• The low viscosity nature of the basaltic magma means there will be a relatively short pre-eruption
period (possibly only a couple of days);
• There may be more than one eruption vent (although it is expected that any vents in a multi-vent
episode will be in relatively close proximity);
• Unlike many other natural hazards in New Zealand, volcanic activity will occur over a relatively long
time period (a period of months up to a year or more); and
• Volcanic activity will give rise to a number of hazards, which will have minor to severe impacts both in terms of damage and geographic extent.
An understanding of the geological character of the AVF and the associated hazards, and formulation of interim and long-term technical solutions, have been fundamental to development of a Volcanic Contingency Plan for Auckland.